Radiolysis of monoolefins with a sensitizer



July 24, 1962 c. E. HEATH ET AL I 3,046,208

RADIOLYSIS OF MONOOLEFINS WITH A SENSITIZER Filed April 29, 1957 ALKYL HALIDE SENSIJIZER RADlO-ALKYLATION 3 ZONE SEPARATION I v ALKYLATE OLEFIN/ T 4 7 PARAFFIN MIXTURE 2 5 Carl E. Heath Inventors Peter J. Lucchesi BYXQ..5ZLM Attorney 3,046,208 RADIOLYSIS F MONOOLEFINS WETH A SENSITIZER Carl E. Heath, Nixon, and Peter J. Lucchesi, Cranford, N..l., assignors to Esso Research and Engineering Company, a corporation of Delaware Filed Apr. 29, 1957, Ser. No. 655,912 8 Claims. (Cl. 204-154) The present invention is concerned with the alkylation of hydrocarbons with monoolefins. It is more particularly directed to the radiation induced reactions of monoolefins With saturated hydrocarbons using as a sensitizer a halogenated hydrocarbon.

In brief compass, this invention proposes a process comprising irradiating a monoolefin reactant containing in the' range of 2 through 8 carbon atoms with high energy ionizing radiation, in the presence of 0.1 to 15 Wt; percent, based on total feed, of a halogenated hydrocarbon containing 1 through 6 carbon atoms, until at least 0.01 kwh. of radiant energy per pound of product has been absorbed. Preferably the monoolefin is in admixture with 99 to 80 wt. percent, based on total feed, of another saturated hydrocarbon containing from 1 through 20 carbon atoms whereby alkylation is obtained.

The product of the alkylation comprises in the range of 20 to 90 wt. percent of hydrocarbons having at least two alkyl side chains and the yield is surprisingly high, being above 40 molecules of feed reacitng per 100 electron volts of radiant energy absorbed.

The alkylate obtained according to this invention has a very high octane number and is especially useful in gasolines.

The attached drawing of one embodiment of this invention, and the following description will serve to make this invention clear.

This invention is broadly applicable to any monoolefin, whether terminally unsaturated or not, but is most useful with terminally unsaturated monoolefins having from 2 to 8 carbon atoms per molecule, such as ethylene, butene and hexene. Mixtures of monoolefins can be irradiated. These monoolefins can be obtained by any conventional means known to the art, e.g., by the separation of a thermally cracked petroleum fraction such as a light naphtha.

Broadly, any hydrocarbon can be alkylated, according to this invention, with the monoolefins. Most interesting are the ones having from 1 through 20 carbon atoms, such as benzene and its homologs, and especially aliphatics, whether normal or branched, containing 2 through 8 carbon atoms. Mixtures of hydrocarbons can be alkylated. These hydrocarbons can be obtained in any convenient manner, "e.g., by separation of crude oils using conventional techniques such as distillation, dewaxing, etc. When carrying out an alkylation reaction, the amount of monoolefin used amounts to preferably 1 to 20 wt. percent of the feed.

The sensitizer used is preferably a halogenated hydrocarbon or alkyl halide containing 1 to 6 carbon atoms, although higher halogenated hydrocarbons may be used. It is preferably vaporous under prevailing reaction conditions, although it can be used in liquid form. contain one or more halogen atoms, up to full halogenation. Examples are carbon tetrafiuoride, carbon tetrachloride, chloroform, dichloroethane, difiuoroethane and bromopropane. The sensitizer can contain two or more different halogen atoms. Examples are dichloro-difluoro methane (Freon 12), trichloromono fluoromethane (Freon 11), and dichlorotetra fluoroethane (Freon 114). The sensitizer molecule can also contain other substitute groups, e.g., a sulfonic, alcohol, carbonyl, peroxide and/ or ether group. Examples of the latter are fluoroethane It can' amazes sulfonic acid, chloropropanol, dibromomethyl peroxide, and chloroethyl ketone. The halogenated hydrocarbon is used in an amount in the range of 0.05 to 10 wt. percent, expressed as halogen, based on feed.

The reaction is preferably carried out in the absence of free oxygen, i.e., in the presence of less than 0.5 wt. percent free oxygen; and also preferably in the absence 01 free hydrogen added to the feed as such. The system can tolerate some inerts such as nitrogen and carbon dioxide, up to about 50 wt. percent. Some inert gases aid in the utilization of the radiant energy and are desirable.

By the term high energy ionizing radiation is meant irradiation from terrestrial sources consisting of photons having a wave length less than 50 A., such as gamma and X-rays; rapidly moving charged or uncharged particles of an atomic or subatomic nature having an energy above 30 ev., such as alpha particles and beta rays; and neutrons. The. irradiation is of sufficient intensity that the dose rate is at least 0.01 kwh./hr./lb. of product. This excludes radiation such as cosmic and ultraviolet, which are ineffectual for the purposes of this invention. It is preferred to use essentially gamma or beta radiation because of the safety and ease of control. So far as known, the reaction is not significantly influenced by the type oi radiation, but only primarily by the dose rate, total dosage, and conditions under which the radiation is received.

The radiation is obtained from any convenient source, such as charged particle accelerators, e.g., Van de Graafl generators; nuclear reactors; radioactive waste products, e.g., spent fuel elements; and materials especially made radioactive, e.g., cobalt 60 and caesium 137. The use 01 radioactive isotopes is especially convenient.

The radiolysis of the feed mixture is carried out by exposing it either continuously or batchwise to the radiation. For example, when a nuclear reactor is used, the

of 100 to 800 F. The dosage received is preferably at least 0.01 kWh/lb. of product. Excessive dosages are to .be avoided and usually not more than 1.0 kWh./lb. oi

product will be necessary. For best results, the dose rate for all types of radiation, whether mixed or pure, should be at least 0.01 kwh./hr./lb. of product to produce a favorable rate of reaction. It is usually not necessary tc use a dose rate above 10 kwh./hr./ lb.

The product obtained from alkylation of hydrocarbons in the preferred embodiment of this invention, has normally 5 to 20 carbon atoms and boils in the range of to 430 F. For the above dosages, this alkylate can be obtained in yields in the range of 2 to 30 wt. percent, based on total feed. Because of the surprising degree of branchiness in the product, it has a high octane rating, usually above 90 Research Clear, and is especially suited for use in or as a gasoline.

In the drawing, an olefin-paraffin mixture is supplied by line 1 to a radio-alkylation zone 2. Zone 2 can comprise any convenient radiation source, such as a nuclear reactor, wherein mixed neutron and gamma ray irradiation is obtained. Line 3 supplies to line 1 a small amount of an alkyl halide sensitizer according to the teachings of this invention. After the radio-alkylation is completed to the extent desired, the product is transferred by line 4 to a separation zone 5. In separation zone 5, any further treatment of the alkylate can be made as desired. For example, a simple distillation can be carried out to remove inreacted hydrocarbons which can be recycled, if desired, )y line 6. The alkylate product is removed by line 7.

EXAMPLE 1 An isobutanc-propylene (8/1 mole ratio) mixture was :onverted in the presence and in the absence of a fiuoro iydrocarbon sensitizer. The isobutane-propylene mixture, with the addition of 1 wt. percent of dichloro-difiuoro nethane (Freon 12), was converted in high yields to C and C isoparaffins when irradiated at 100 F. with gamma radiation obtained from a cobalt 60 source. The source was in the form of a two-inch O.D. hollow pipe and vrad a rating of about 3000 curies. The radiation was continued at a rate of about 1.0 megaroentgens per hour (one megaroentgen equals approximately 3.62 B.t.u.s per pound of radiation), until a dosage of 65 megaroentgens sad been received. The radiation yield in terms of two molecules of feed reacting to form one molecule of prodact, was 43 molecules per 100 electron volts. The yield was 135 wt. percent based on olefin.

When the isobutane-propylene mixture was irradiated in the absence of the fluorocarbon, the radiation yield on the above basis was 26 feed molecules reacted per 100 ev., the radiation being carried out on the same conditions. The product contained 56% of isoparaflins and the remainder of C liquid product was C dimer.

Table I presents the results of these irradiations and shows the surprisingly high yield of branehiness obtained in the irradiation of the mixture containing the dichlorodifluoro methane sensitizer.

l Isoparaifin fraction is 90 Wt. percent of total 65+ product.

9 Isoparafiin fraction is 56 wt. percent of total C product.

3 GLPC (Gas-Liquid Partition Chromotography) used to obtain these results does not distinguish between these isomers.

Nora-Title abbreviations used in tables: DMBDimethyl butane; MP-Methyl pentane; DMPDimethyl pentane; MHMethyl hexane; EPEthyl pentane.

EXAMPLE 2 A mixture of 8 moles of isobutane and one mole of propylene was irradiated in the source described in Example I at a temperature of 500 F. and a pressure of 800 psi. in the vapor phase. The dose rate was 1.5 X 10 roentgens per hour of gamma radiation, and the total dosage received was 9.3 megaroentgens. One run was carried out in the presence of 1.0 Wt. percent chloroform as a sensitizer, and the other was carried out in the absence of a sensitizer. Table II gives the results of these irradiations, and Table III gives an inspection of the products.

Table III Yield, Wt. Percent on Iso 0 -150 0 Compound With Without OHCl; CHCl;

1 GLPC does not distinguish between these compounds.

It can be seen that the chloroform had an appreciable effect on the yield and on the type of products obtained from the radio-alkylation.

It was expected that conventional alkylation catalysts might also be used as sensitizers. The use of hydrogen fluoride in alkylation tests of the same nature as above, both in the liquid and in the vapor phase, proved unsuccessful.

COMPARATIVE EXAMPLE 1 A mixture of 8 moles of isobutane and 1 mole of propene was irradiated in the liquid phase at 150 F. in the source described in Example 1, until 65 megaroentgens of radiation had been absorbed. Table IV shows that no significant improvement was noted with the hydrogen fluoride sensitizer, as compared to radio-alkylation in the absence of hydrogen fluoride.

pylene was irradiated in the vapor phase in the source described in Example 1, and 500 F. until 9.3- megaroentgens of radiation had been absorbed. Table V shows that the presence of 1.0 wt. percent of hydrogen fluoride as compared to a run made in the absence of hydrogen fluoride, did not give significantly different results.

Table V 0 Yield Radiation Yield. Feed Wt. Per- Wt. Per- Molecules cent on cent on Reaeted/ Olefin Fed Olefin 0011 ev.

sumed With 1 Wt. percent HF 51 55. 5 116 Without 53 95 COMPARATIVE EXAMPLE 3 Table VI shows a comparison between the present sen. sitized radio-alkylation process, and the sulfuric acid alkylation process known to the prior art.

It can be seen that the product distribution as well as the yield of isoparaffins of the present radio-alkylation process are substantially different from the results obtained by the prior arts sulfuric acid process.

The invention having been described, what is sought to be protected by Letters Patent is succinctly set forth in the following claims.

What is claimed is:

1. A- process comprising irradiating amonoolefin reactant containing 2 to 8 carbon atoms in admixture with 99 to 80 Wt. percent of a saturated'hydrocarbon containing from 1 to 20 carbon atoms with high energy ionizing radiation equivalent to at least 30 electron volts in the presence of 0.1 to wt. percent, based on total feed, of a halogenated hydrocarbon containing 1 to 6 carbon atoms, until in the range of 0.01 to 1.0 kwh. of radiant energy per pound of product has been absorbed, and thereby obtaining a product comprising in the range of to 90 wt. percent of hydrocarbons with at least 2 alkyl side chains.

2. The process of claim 1 wherein the temperature is in the range of 100 to 800 F. and the radiation is carried out substantially under vapor phase conditions.

3. The process of claim 1 wherein said product boiling in the range of 90 to 430 F. amounts to 2 to 30 wt. percent, based on total feed, and has a Research Clear octar number above 90.

4. A process comprising irradiating a terminally ui saturated monoolefin having from 2 to 8 carbon atoms i admixture with 99 to wt. percent of a saturated al phatic hydrocarbon having from 2 to 8 carbon atoms wit high energy ionizing radiation equivalent to at least 3 electron volts at a rate in the range of 0.01 to 1 kWh./hr./lb. of product at a temperature in the range c 100 to 800 F., until in the range of 0.01 to 1.0 kWh/ll of product of radiant energy has been absorbed, the re actants containing 0.1 to 15 wt. percent of an alkyl halid sensitizer containing from 1 through 6 carbon atoms, an thereby obtaining a product comprising in the range c 20 to 90 wt. percent of hydrocarbons with at least 2 alky side chains.

5. The process of claim 4 wherein the alkyl halide i dichloro-difluoro methane, the monoolefin is propylene and the other hydrocarbon is isobutane.

6. The process of claim 4 wherein the alkyl halide i chloroform, the monoolefin is propylene, and the othe hydrocarbon is isobutane.

7. Process as defined by claim 1 wherein at least weight percent of said halogenated hydrocarbon is present based on feed.

8. The process of claim 4 wherein the reactants con tain at least 1 weight percent of said alkyl halide sensi tizer.

References Cited in the file of this patent UNITED STATES PATENTS 2,636,853 Franklin Apr. 28, 1952 2,743,223 McClinton et a1 Apr. 24, 1951 2,872,396 Wilson et a1 Feb. 3, 195. FOREIGN PATENTS 708,901 Great Britain May 12,

714,843 Great Britain Sept. 1, 195

OTHER REFERENCES Bourne et al.: Chem. & Ind., pages 1372-1376, Nov 24, 1956.

Charlesby Proc. Roy. Soc. (London), vol. 222A, page 6074 (Feb. 23, 1954). 

1. A PROCESS COMPRISING IRRADIATING A MONOOLEFIN REACTANT CONTAINING 2 TO 8 CARBON ATOMS IN ADNIXTURE WITH 99 TO 80 WT. PERCENT OF A SATURATED HYDROCARBON CONTAINTNG FROM 1 TO 20 CARBON ATOMS WITH HIGH ENERGY IONIZING RADIATION EQUIVALENT TO AT LEAST 30 ELECTRON VOLTS IN THE PRESENCE OF 0.1 TO 15 WT. PERCENT, BASED ON TOTAL FEED, OF A HALOGENEATED HYDROVARBON CONTAINING 1 TO 6 CARBON ATOMS, UNTIL IN THE RANGE OF 0.01 TO 1.0 KWH. OF REDIANT ENERGY PER POUND OF PRODUCT HAS BEEN ABSORBED, AND THEREBY OBTAINING A PRODUCT COMPRISING IN THE RANGE OF 20 TO 90 WT. PERCENT OF HYDROCARBONS WITH AT LEAST 2 ALKYL SIDE CHAINS. 